ismith
09-04-2008, 04:54 PM
Finally got some ECU errors come through with my long-standing poor mpg. "Lambda (Oxygen Sensor) Regulation - Control Limit Not Reached - Intermittent" Any ideas?
The plugs are a little black, not normal. I've tried an ECU reset and training procedure.
The blue sensor was replaced a couple of years ago. With logging on VAG COM, it warms up beautifully in a sensible ramp from cold to 85C. The lambda readings start changing at 60.
The lambda was faulty once before and replaced last year and appears fine now - 0.95-1.05 on VAG COM when idling. The weird thing is the range of ADAPTATION values for idle, mid and full throttle (group 6). This previously was 0.9xx-1.0xx, but now anything from 0.400 to 0.999. (Today 0.415 0.992 0.922) I also checked the wiring from ECU to lambda and MAF and the supply to the lambda heater is good.
The injectors have been overhauled and I've tried a new MAF. The fuel pressure is spot on (3.5 bar idling, 4.0 bar on throttle blip.) Compressions cold and hot are well within spec, although there is some oil consumption (around 0.5 l /1000 miles). I also checked the evap purge valve closes after start. The crankcase breather pipe is good too.
Is my ECU failing?
The plugs are a little black, not normal. I've tried an ECU reset and training procedure.
The blue sensor was replaced a couple of years ago. With logging on VAG COM, it warms up beautifully in a sensible ramp from cold to 85C. The lambda readings start changing at 60.
The lambda was faulty once before and replaced last year and appears fine now - 0.95-1.05 on VAG COM when idling. The weird thing is the range of ADAPTATION values for idle, mid and full throttle (group 6). This previously was 0.9xx-1.0xx, but now anything from 0.400 to 0.999. (Today 0.415 0.992 0.922) I also checked the wiring from ECU to lambda and MAF and the supply to the lambda heater is good.
The injectors have been overhauled and I've tried a new MAF. The fuel pressure is spot on (3.5 bar idling, 4.0 bar on throttle blip.) Compressions cold and hot are well within spec, although there is some oil consumption (around 0.5 l /1000 miles). I also checked the evap purge valve closes after start. The crankcase breather pipe is good too.
Is my ECU failing?